This is a new Gear motor version of my previous Linear Servo actuator (http://www.thingiverse.com/thing:308576) It is a custom 3D printed Linear Servo actuator for activating a lever or push/pulling something or other. In this version I have designed the guide rails into the body of the actuator (for protection and a sturdier steadier motion). The feedback gear also incorporates a lug which slots into the feedback potentiometer spindle. If you would like to build it ot see it in action then head over to http://youtu.be/6VY1zWZcvO0 for assembly details It uses a general purpose Geared Motor (often refereed to as a GM motor) This version is faster and stronger than my original design. Specs :- Stroke :- 45mm Speed :- Circa 1cm/sec using a 2 cell Lipo battery Force :- Easily 3Kg (my kitchen scale max_ed out so could not measure over 3Kg) More details can be found here :- http://hackaday.io/project/1011-Linear-Servo-Actuator-%28GM%29-Gear-Motor-Version